The front wheel of a motorcycle typically is mounted rotatably on an axle or spindle spanning the free ends of two parallel legs of a front fork which is pivotably connected to a main frame of the motorcycle for steering movement of the front wheel. The front fork usually incorporates a pair of telescopic shock absorbers, one for each leg of the fork. The shock absorbers may contain both compression springs and hydraulic fluid to absorb the jolts and shocks caused by bumps and other irregularities of the surfaces traveled by the motorcycle. For a front end in which the wheel including its hub rotates around the axle as the motorcycle travels, a conventional braking system may comprise a friction producing means which for braking purposes arrests rotational movement of the front wheel through a fixed braking member being brought into contact with an adjacent braked member mounted on the hub of the rotating wheel. For instance, the braking member may comprise brake shoes carried by a plate, or brake pads carried by an actuating caliper, with the plate or caliper being secured to a fork leg or to a non-rotatable axle fixedly connected with the fork legs. The actuation of a braking member's shoes or pads into a friction contact with a rotating braked member may be accomplished by mechanical lever movement or by movement of pistons of hydraulic brake cylinders which are controlled by the motorcycle operator through such means as hand brake levers. As is known for a motorcycle incorporating this form of front wheel suspension and braking, the telescopic shock absorbers undergo compression upon braking, with the motorcycle's front end dipping or diving, and diving quite severely upon hard braking. This front end diving upon braking can be hazardous, with a resultant loss of operator handling stability and control of the motorcycle.
The art has recognized some of the dangers arising from a motorcycle's front end diving upon braking, and a variety of approaches and means have been tried for alleviating this dive problem. U.S. Pat. No. 3,989,261, Kawaguchi, discloses a motorcycle front-wheel suspension with means for restraint of compression of a telescopic front end upon braking. In one embodiment a torque force from braking is utilized, as through a leverage mechanism, to lock the telescopic shock absorbers of the front fork against compression. In another, a leverage mechanism closes a valve to shut off hydraulic fluid flow between chambers of the telescopic front fork. U.S. Pat. No. 3,899,049, Martin, while principally concerned with motorcycle brakes, in its FIG. 4 refers to a torque take-up arm of use with a motorcycle rear wheel, but which would not be useful for the front wheel.
The present invention is not limited to an off or on type of control as in the Kawaguchi suspensions, but provides a smoothly increasing force to oppose the diving action that ordinarily accompanies braking. It also provides a gradually decreasing force as the brake is released, and thus avoids any noticeable overshoot or upsurging by the front end. Other features of the invention, such as its adjustable damping, also add to the safety and comfort of the person operating the vehicle and of any other occupant.